- The technique basically follows the recommendation of Dhand and Guntur. Airway secretions should be sucked out before drug administration. Heat moisture exchanger, but not humidifier, is removed. After shaking and warming MDI to hand temperature, the canister is connected to an AeroChamber HC MV spacer (Trudell Medical International, London, Canada) placed in the inspiratory limb of ventilator circuit 15 cm away from the endotracheal tube. Actuation is synchronized with the initiation of inspiration. Each actuation is at least 15 second apart.